Hitherto, it has been a widely and commonly used technology to grip a workpiece by means of a gripping mechanism, and to produce products by removing material from a part of the workpiece. Various technologies are known to facilitate positioning in gripping of the workpiece, and to shorten production time.
When a part, such as the part shown in FIG. 3, is to be produced as a product 550 for example, it is known to use a long round bar as a workpiece 500 as shown in FIG. 16 to produce a plurality of products 550. It is possible to produce the plurality of products 550 consecutively by setting the workpiece 500 once, repeating the cutting, i.e., material removing, steps, separating parts of the workpiece 500 while gripping the workpiece by means of a gripping mechanism provided on the spindle of an automatic lathe, and sequentially feeding and then positioning the workpiece 500. The positioning, of the workpiece is carried out each time a product is completed by feeding the workpiece so that an end thereof abuts a positioning stop, and by gripping the workpiece at that position, as described in the specification and drawings of Japanese Patent No. 3954965, for example.
As shown in FIGS. 17 and 18, it is also known to produce a product 550 by first forming a raw blank 501 having an external shape slightly larger than, but analogous to, the outer shape of the product 550, and then repeatedly removing material while gripping each raw blank individually and sequentially by means of a gripping mechanism provided on the spindle of an automatic lathe.